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OT: Porter Cable charger

karl

Cast Iron
Joined
Sep 11, 2005
Location
Fayetteville, close to Pond Bank, Pa.
Hello,
I have a very old, 25 years, Porter Cable 12 Volt drill/driver model 853. I had the NiCad battery packs rebuilt with higher capacity cells and the charger died as a result. The voltage regulator is NLA and I have been unable to find anyone who supports this unit. Is there any reason that a "smart charger" used by the radio control folks wouldn't charge the batteries safely? Thanks for your help. Karl
 
Old NiCads were always constant current charged. Sort-of like get a string of batteries rated at 3A/Hr. This means the .1C charge is .3A. So connect batteries to a charger, adjust a resistor at its output so max current is .3A, switch on, come back in 10 hours and batteries are charged.
The later chargers(often on electric drills), use a diode which measures the temperature of the batteries and reduces the charge. These charge batteries in a matter of hours.
The later generation of chargers, put the power into the batteries as a series of pulses, the voltage change between the pulse "on" and "off" is used to determine if more or less current is required. Again charges in hours.
In general the life of NiCads is shortened by high temperatures evaporating the eloctrolyte, the " modern" systems tend to do this.
Frank
 
I have been buying battery operated drills & saws without chargers for years at flea markets and auctions. Latest was a like new Black & Decker drill, circular saw, and reciprocating saw, & case, no battery or charger. All for $20.

Got a battery from a hock shop. It wasn't taking a charge, so free. I charged & discharged it several times and it works long enough for what I use them for.

I have a variable output model airplane battery charger with an amp meter and a 15 minute charge timer.

I have alligator clips on the charger wires and clip on, or hold against the contacts on the battery with a rubber band. Be sure to observe polarity.

It is best with Nicads to run the battery down until the drill barely turns.

I give it 15 minutes at about 3 amps, then again. When the charge rate drops, you are charged.

I have done the same thing with another charger with no time limit and fried two sets of batteries. Killed some cells and melted the housing so it wouldn't go into the tool.

Another approach is to adjust the no load (turned on, but unconnected to the battery) charger voltage to 13 volts for a 12 volt battery and put it on the battery overnight. This will gently charge the battery and then float along at full charge.

Overcharging quickly can cause the cells to burst and possibly cause a fire.

You are your own safety officer.

Paul
 
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It is best with Nicads to run the battery down until the drill barely turns.

I disagree. If you do this, you risk cell reversal if one or more of the individual cells isn't holding as much charge as the rest of the pack. Once that happens, you've seriously reduced the life of the pack because the affected cells do not fully recover.

A better maintenance strategy is to stop using the tool and recharge as soon as it starts to noticeably loose power, then occasionally slow charge the pack to equalize the cells.
 








 
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